The present invention relates to a guide roll in general, and in particular to a multi-partite guide roll. The guide roll of the present invention is especially but not exclusively suited for use in continuous casting installations.
In continuous casting installations the cast slab or billet of metallic material, which is of a great length and moves continuously, must be appropriately guided by means of guide rollers. Usually, the casting is effected in vertical or near-vertical direction so that the slab moves vertically through a certain distance and is thereupon deflected to more or less horizontal direction of movement. For this purpose, guide rolls are provided. However, one-piece guide rolls have been found unsatisfactory if the slab being cast is relatively wide (in axial direction of the roll) and/or is to be cast rapidly so that it travels at relatively high speed. The prior art has proposed under these circumstances to replace the conventional one-piece guide rolls with guide rolls which are composed of a plurality of individual roll sections mounted on a common shaft which supports the individual roll sections for free rotation independently of one another. Because of the great heat to which these roll sections are subjected from the still hot (usually incondescent) cast slab or billet, the rolls are cooled by spraying cooling liquid onto them from the exterior, a measure which is also practiced in connection with one-piece rolls.
This manner of cooling is satisfactory for one-piece rolls. However, it has been found that it is not satisfactory in multi-partite guide rolls where individual roll sections are mounted for free independent rotation on a common shaft. The problem is that frequently only some of the roll sections of a guide roll will be in contact with the advancing slab or billet and will be frictionally turned by the same, whereas one or more other roll sections of the same guide roll will not be in contact and will therefore be stationary. When this happens, one and the same surface portion of the stationary roll section will always be facing towards the advancing slab or billet and will therefore receive the full effect of the heat radiated thereby. Spraying water onto the thus-stationary roll sections is no longer sufficient, under these circumstances, to cool them adequately; as a result, these roll sections including the bearings which mount them for free rotation on the common shaft of the roll, become heated to such an extent that they are destroyed or at least very substantially damaged. If subsequently the billet again frictionally engages the thus-damaged roll sections, these roll sections are no longer able to turn and block proper advancement of the billet. When this happens the only remedy normally available is to stop the continuous casting installation, and wait until the billet has cooled, remove the billet, remove the guide roll and replace it with another one or at least replace the damaged roll sections and the bearings thereof, and reinstall the guide roll. It is evident that the machine down-time involved, and the labor required to correct such a problem, mean substantial economic losses which heretofore have had to be accepted, absent a more satisfactory solution, but which evidently are undesirable.